This invention is directed to lubricant additives and compositions thereof, and more particularly to liquid hydrocarbyl fuels and lubricant compositions, comprising said fuels or oils of lubricating viscosity or greases prepared therefrom containing friction reducing amounts of imidazoline salts of acid phosphates derived from hydrocarbyl diols or mixtures thereof.
Phosphorus-containing additives have been extensively used in lubricant applications. These additives include phosphites, phosphate esters, acid phosphates, phosphonates, metallic dithiophosphates and the like.
Imidazolines have found use as friction reducing additives as described in U.S. Pat. Nos. 4,394,278 and 4,298,486. U.S. Pat. No. 4,427,562 discloses imidazolines and certain esters thereof as known antifriction additives. U.S. Pat. No. 4,163,731 is directed to certain fire resistant functional fluids based on phosphate esters and substituted aromatic compounds, as for example, heterocyclic compounds such as imidazolines.
Hydroxy-containing additives and their derivatives are well-known for their water scavenging properties when formulated into fuels and for their lubricity characteristics when blended into lubricants. The use of glycerol monooleate and similar hydroxyl-containing carboxylates have found wide spread commercial use as lubricant additives. The use of related diols is described in U.S. Pat. Nos. 3,649,358 and 3,899,433.
The hydrocarbyl-diol derived imidazoline salts of acid phosphates as disclosed herein contribute excellent friction reducing properties when formulated at low additive concentrations into hydrocarbyl fuels, fluid lubricants and greases. The modest acid phosphate content provides the basis for significant synergistic wear activity in the highly surface active molecules of the embodied products. The basis for antirust and anticorrosion properties is provided by the nitrogen-containing heterocyclic moiety, particularly the imidazoline-containing acid phosphates.
To the best of applicants' knowledge and belief, both the additive structures per se and the lubricant compositions containing such additives are novel. Further, the unique compositions disclosed herein are not known to have been previously used as multifunctional friction reducing antiwear or antirust additives in hydrocarbyl lubricating oils, greases, or fuels.